Newton's Laws
Sir Isaac Newton lived during the 1600s. Like any good scientist, he made observations about the world around him. Based on his observations he developed his now famous three laws of motion. Although he lived hundreds of years ago, his work continues to be viewed as one of the most important contributions to science. His laws of motion explain rest, constant motion, accelerated motion, and describe how balanced and unbalanced forces act to cause these states of motion.
Have you 
ever
been riding in a car when the driver suddenly slammed on the brakes? How
did your body move as the car came to a stop? You probably felt your body
move forward. When you felt this happening you experienced Newton's first
law of motion. Newton's first law of motion says that an object
in motion will stay in motion and an object at rest will stay at rest
unless acted on by an unbalanced force. In the car your body was in
motion, traveling at the same speed as the car. When the car stopped,
your body stayed in motion. If you were not wearing a seatbelt and you
were traveling very fast, your body could continue to move forward through
the windshield!
Newton called his first law inertia.
Try
the following activity to demonstrate this law!
- Place a 3x5 card on top of a glass.
- Put a coin on the center of the card.
- Flick the card horizontally with your finger.
- What happens to the coin?
- Explain what happened to the coin using Newton's first law.
This
activity is similar to the magician's trick of pulling a tablecloth out
from under dishes on a table. Because the dishes have inertia, they will
stay at rest unless acted on by some unbalanced force. If the tablecloth
is really smooth and is pulled out fast enough, there is not enough friction
created to cause the dishes to move. DO NOT TRY
THIS AT HOME WITHOUT PARENT PERMISSION!
